Solid State NMR Investigation of C1-Deuterated Poly(di-n-hexylsilylene)

Phase Behaviour of Poly(di-n-decylsilane)

“…The spectrum recorded at 304 K, near the transition to the intermediate state, is a superposition of several fractions: the almost rigid one with a splitting of 119 kHz at this temperature (probably state I), a more mobile fraction with a reduced quadrupolar splitting of about 85 kHz (probably state II), the beginning mesophase (Áv of 23 kHz) , and ®nally a small amount of an amorphous fraction giving rise to the narrow isotropic peak in the center. The spectra in the mesophase are similar for all polysilanes studied so far [6,7], indicating that the dynamic processes are the same in all compounds. These spectra are motionally narrowed by a factor of about 1/5, making evident that the Si chain is also involved in the motions.…”

“…Above the transition to the mesophase at 322 K, motionally narrowed powder spectra are obtained with splittings of about 23 kHz. A splitting of this size is characteristic of the mesophase of polysilanes [6,7]. The spectral shape re¯ects the axial symmetry of the molecular motions, and the narrow width proves the highly dynamic nature of both side and main chains.…”

Columnar Phase-Forming Polymers

“…Solid-state NMR and thermal analysis have been utilized to study the crystallinemesophase transition of PDmSis with m = 4, 5, 6 (Schilling et al 1986(Schilling et al , 1989bMüller et al 1996), and 14 (Varma-Nair et al 1991). Entropy analysis suggested that there are about two CH 2 units in each side-chain not gaining disorder from the lowest temperature crystalline phase to the mesophase (Varma-Nair et al 1991).…”